Event Overview

A magnitude Mw 8.2 earthquake ruptured the subduction zone off the coast of northern Chile at 11:46:46 p.m. GMT on April 1, 2014. The event occurred in the "Iquique seismic gap," a segment of the Nazca-South American subduction zone that had not experienced a significant event since 1877. The earthquake was preceeded by multiple smaller events including a Mw 6.7 earthquake on March 16, 2014 followed by more than 80 earthquakes of Mw 4 or greater. Notable aftershocks include an Mw 6.5 event and an Mw 7.6 event less than an hour apart on April 3, 2014. For more information, see the USGS Earthquake Hazards Program event summary.

Geodesy in Northern Chile

Caltech, in collaboration with colleagues at the Universidad de Chile, Instituto Geofisico del Peru, Universidad de Arica (now Tarapaca), and Universidad del Catolica Norte, built a 25-station GPS network throughout southern Peru and northern Chile between 2005 and 2011. Researchers built the network to measure the slow but substantial deformation caused by subduction of the Nazca plate eastward beneath the South American plate. Because the area had accumulated substantial strain, measuring displacement during a great earthquake like the one that last occurred in northern Chile in 1877 was also likely. The recent magnitude 8.2 Iquique earthquake was not that expected great earthquake, but it certainly plays a role in the earthquake cycle of this region.

The Caltech stations set the example for the growing Chilean and Peruvian national GPS networks by using the UNAVCO-advocated shallow drilled-braced monument design and the GPS, communication, and ancillary equipment. Stations of the Integrated Plate Boundary Observatory Chile (IPOC) complement the Caltech stations with few or no redundant stations. The bulk of funding to build the Caltech stations came from the Gordon and Betty Moore Foundation, with additional funding from NSF that qualifies the data for archiving at UNAVCO. Pre-event data (2005-present) are available now, and we expect to provide co-seismic 15-second and 5-Hz sample rate data once a Universidad de Chile field team returns to Santiago from a visit to stations in the region.

Figure 3. Left: The unwrapped phase displacement in the radar line-of-sight showing subsidence and westward motion (both away from the satellite) of more than 60 cm. Right: The wrapped interferogram; each fringe shows...Read more »

Figure 4. Preliminary results for Ionospheric Total Electron Content (TEC) measurements show precursory anomalies for the 2014 Mw 8.2 Iquique earthquake at GPS site IQQE, 100 km SE of the epicenter. The top figure shows...Read more »

Figure 6. Shear strain from the Mw 8.2 April 1, 2014 earthquake off the coast of northern Chile as recorded by a selection of Plate Boundary Observatory borehole strainmeters. Shown are 1-sample-per-second high-rate...Read more »

Figure 7. IGS station IQQE during installation in June 1996 with IGM-Chile employee Patricio Gallardo preparing the foundation for the equipment enclosure (left) and Eric Kendrick of The Ohio State University standing...Read more »

Figure 8. Modeled displacements at continuous GPS sites in northwest Chile for the day of (top) and the day after (bottom) the Mw 8.2 mainshock event. Figure provided by Dr. Jeffrey Freymueller, University of Alaska...Read more »

Figure 9. The main shock and aftershocks of the Mw 8.2 April 1, 2014 earthquake off the coast of northern Chile. (Map produced using the UNAVCO Jules Verne Voyager tool with earthquake data from the USGS National...Read more »

Figure 11. Tide gauge data from station Iquique_CL on the Chilean coast. Shown is a screen capture from the UNESCO/IOC Sea Level Station Monitoring Facility. The tsunami resulting from the Mw 8.2 event reached heights of...Read more »

UNAVCO Event Response Support

UNAVCO is in the process of assisting scientists and field personnel in need of support including instrumentation acquisition and deployment, geodetic data acquisition, and proposal preparation. Our Event Response Coordinators for Iquique are:
Dr. Freddy Blume blumeunavco.org
John Galetzka galetzkaunavco.org

Field-ready campaign GPS systems are available for deployment if requested.

Map Center: Iquique, Chile

UNAVCO Community Discussion Forum

Links to GPS, strainmeter and satellite data and data products, results from the UNAVCO Community, and moderated public discussion. Results and status updates may be posted by the public (registration required).